Germany is about to start up a monster machine that could revolutionize the way we use energy

For more than 60 years, scientists have dreamed of a clean,
inexhaustible energy source in the form of nuclear fusion.

And they're still dreaming.

But thanks to the efforts of the Max Planck Institute for Plasma
Physics, experts hope that might soon change.

Last year, after 1.1 million construction hours, the institute
completed the world's largest nuclear-fusion machine of its kind,
called a stellarator.

The machine, which has a diameter of 52 feet, is called the W7-X.

And after more than a year of tests, engineers are finally ready
to fire up the $1.1 billion machine for the first time. It could
happen before the end of this month, Science
reported.

The black horse of nuclear reactors

Known in the plasma physics community as the "black horse" of
reactors that use nuclear fusion, stellarators are notoriously
difficult to build.

The GIF below shows the many different layers of W7-X, which took
19 years to complete:

Your browser does not support the video tag.
science

From 2003 to
2007, as the project was being built, it suffered some major
construction setbacks — including one of its contracted
manufacturers going out of business — that nearly canceled the
whole endeavor.

Only a handful of stellarators have been attempted, and even
fewer have been completed.

By comparison, the more popular cousin to the stellarator, called
a tokamak, is in wider use. Over three dozen tokamaks are
operational around the world, and more than 200 have been built
throughout history. These machines are easier to construct and,
in the past, have performed better as a nuclear reactor than
stellarators.

But tokamaks have a major flaw that W7-X is reportedly immune to,
suggesting that Germany's latest monster machine could be a game
changer.

How a nuclear-fusion reactor works

The key to a successful nuclear-fusion reactor of any kind is to
generate, confine, and control a blob of gas, called a plasma,
that has been heated to temperatures of more than 180 million
degrees Fahrenheit.

At these blazing temperatures, the electrons are ripped from
their atoms, forming ions.

Normally, the ions bounce off one another like bumper cars, but
under these extreme conditions the repulsive forces are overcome.

The ions are therefore able to collide and fuse together, which
generates energy, and you have accomplished nuclear fusion.
Nuclear fusion is different from what fuels today's nuclear
reactors, which operate with energy from atoms that decay, or
break apart, instead of fusing together.

Nuclear fusion is the process that has been fueling our sun for
about 4.5 billion years and will continue to do so for another
estimated 4 billion years.

Once engineers have heated the gas in the reactor to the right
temperature, they use super-chilled magnetic coils to generate
powerful magnetic fields that contain and control the plasma.

The W7-X, for example, houses 50 six-ton magnetic coils, shown in
purple in the GIF below. The plasma is contained within the red
coil:

The difference between tokamaks and stellarators

For years, tokamaks have been considered the most promising
machine for producing energy in the way the sun does because the
configuration of their magnetic coils contains a plasma that is
better than that of currently operational stellarators.

Schematic of
W7-X.Science Magazine on
YouTube

But there's a problem: Tokamaks can control the plasma only in
short bursts that last for no more than seven minutes. And the
energy necessary to generate that plasma is more than the energy
engineers get from these periodic bursts.

Because of the stellarators' design, experts suspect it could
sustain a plasma for at least
30 minutes at a time, which is significantly longer than any
tokamak. The French tokamak "Tore Supra" holds the record: Six
minutes 30 seconds.

If W7-X succeeds, it could turn the nuclear-fusion community on
its head and launch stellarators into the limelight.

"The world is waiting to see if we get the confinement time and
then hold it for a long pulse," David Gates, the head of
stellarator physics at the Princeton Plasma Physics Laboratory,
told Science.

Check out this awesome time-lapse video of the construction of
W7-X on YouTube, or
below: